One of the phrases in the 14th is that the debts of the United States shall not be questioned. You could take that to mean that debt must be serviced, no exceptions, and if congress won't do it, the executive must. Needless to say, this interpretation has never been tested in court.
Who knows? Congress has already abdicated its warmaking powers. Maybe they're incapable of handling the purse as well. Shades of Cato and the optimates. Fortunately, Obama is no Julius Caesar.
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